A time where two or more bros sit in a hot tub and engage in Deep Bro Talk (A serious talk between two close male friends, in which they talk about all the things going on in their life at the moment. Deep bro talks are sacred meetings, and all the things discussed during them cannot be told to anyone else without the other's consent.) See Deep Bro Talk Definition.

Bro! 1: Hey do you want to go bro tub today and talk about how God is moving in your life?
Bro! 2: Sure! Let me get my swimming trunks and invite some more bro's!